Summary  
This chapter explains how to use for-loops to iterate over sequences and accumulate results by updating a running total with each loop iteration.

General domain of usage  
Personal data tracking (e.g., aggregating daily expenses or steps)

When you find yourself repeating the same calculation over and over—like adding up daily expenses or tracking steps walked each day—a **for-loop** can save you time and effort. In Python, a **for-loop** lets you automate repetitive actions by running a block of code multiple times, once for each item in a sequence. This is especially useful for everyday tasks where you need to process similar data points, such as daily spending or habit tracking.

# Summing daily expenses over a week using a for-loop
daily_expenses = [12.50, 9.75, 15.20, 8.40, 11.60, 14.30, 10.00]
total_expense = 0

for expense in daily_expenses:
    total_expense += expense

print("Total weekly expense:", total_expense)

In the example above, the list `daily_expenses` stores your spending for each day of the week. The for-loop goes through each `expense` in the list and adds it to `total_expense`. This process is known as **accumulating a total**. The function `range()` is often used with loops when you want to repeat an action a specific number of times. The `range()` function produces a sequence of numbers, which you can use to control how many times the loop runs. A **loop variable** (like `expense` in the example) takes on each value from the sequence, one at a time, allowing you to perform calculations with each item.

# Calculating total steps walked in a week using a list and a loop
steps_per_day = [7000, 8200, 9000, 7500, 8800, 10000, 6500]
total_steps = 0

for steps in steps_per_day:
    total_steps += steps

print("Total steps walked in the week:", total_steps)

What does the `range()` function produce in a for-loop?

How can you accumulate a total inside a loop?

Master practical Python skills for everyday tasks, from calculations and data organization to visualizing information and automating routines. This course blends engaging theory with hands-on challenges, empowering you to solve real-world problems efficiently using Python.

Learn to use Python for automating calculations and streamlining daily routines, from budgeting to simple reminders.

Discover how Python can help you organize, analyze, and summarize everyday data, from to-do lists to simple statistics.

Learn to create simple visualizations and formatted outputs to communicate information clearly and effectively.

Automating Repetitive Tasks with Loops

1. What does the `range()` function produce in a for-loop?

2. How can you accumulate a total inside a loop?

3. Fill in the blanks to complete a loop that sums a list of numbers:

Automating Repetitive Tasks with Loops

1. What does the range() function produce in a for-loop?

2. How can you accumulate a total inside a loop?

3. Fill in the blanks to complete a loop that sums a list of numbers:

1. What does the `range()` function produce in a for-loop?